Automatic compensation means for aerotube fire alarm systems



April 18, 1939. F. MOCOWAN Er AL 2,155,345,

AUTOMATIC COMPENSATION MEANS FOR AEROTUBE FIIRE ALARM SYSTEMS Filed June22, 1934 v lAT'romu-:Y

Patented Apr. 18, 1939 UNTED STATES PATENT OFFICE AUTOMATIC COMPENSATIONMEANS FOR AEROTUBE FIRE ALARM SYSTEMS Application June 22, 1934, SerialNo. 731,820

16 Claims.

The present invention relates to an improvement in apparatus forcontrolling re alarm systems, and more particularly relates tocontrolling operative nre alarm systems of the heat sensitive expansivefluid, tube type, hereinafter to be denoted as aero-tube systems.

Many systems of this kind operate to cause an alarm when the rate ofrise of the temperature exceeds a predetermined maximum rate, as in caseof a dangerous re. Where blower heater devices are used, the rate ofrise, on the starting up` of said device, may be great enough to cause afalse alarm.

Therefore, an object of the present invention is to provide means forautomatically preventing the false alarm during the intentional rapidraising of the temperature.

Another object of the invention is to provide means for automaticallychanging the alarm system so that it will not cause an alarm when thenormal rate of rise for which the system is set is reached, but willautomatically change to send an alarm only when a predetermined higherrate of rise is reached.

Another object of the invention is to automatically restore the system,after a predetermined time, to operate again on the normal rate of rise.

Aero-tube systems for re alarm signalling are usually set to operate onan expansion pressure of about 1.04 ounces per square inch, the.detector being set at an alarm point for per'- mitting a temperaturerise of about ten degrees a minute; if the temperature in the protectedarea rises faster than this the fire alarm is operated. It is understoodthat they detector may be set to any desired degree of rate-of-rise andthe figures herein given are only by way of illustration.

Due to recent introduction of a new room heating and heat dispersionapparatus known as the blower-heater system wherein a motor driven fan,or blower, drives and disperses a large volurne of heated air into aroom from an airL heating source, trouble from false alarms in aerotubeprotected areas has been encountered, for the reason that suchheater-blowers deliver such increased volumes of heat as to exceed thenormal rate-of-rise of the aero-tube system and therefore the detectorsends in an alarm. l

The present device is so designed that extraction of a volume of airfrom the aero-tube system which is substantially equivalent to theexpanded air therein prevents the detector from sending in an alarm byreason of the pressure in the aero-system being maintained substantiallyconstant over the period of rapid room temperature change. After the rstrush of heated air the aero-tube system gradually adjusts. back tonormal rate-of-rise control of the detectors 5 and is ready to delivertrue lire alarm signals.

The foregoing and other features of advantage Will be apprehended as thedescription herein proceeds and it is obvious that modications may bemade in the herein apparatus without depart- 10 ing from the spirithereof or the scope of the appended claims.

The drawing herein is illustrativeof the instant invention in detail butis purely diagrammatic in such portions of the coacting apparatus 15 asare old in the aero-tube signalling systems.

In the drawing,

Fig. 1 is a side elevation of the diaphragm valve with its protectiveouter housing out away to better show the interior portions, including aconventional detector alarm means, shown in section and connected to anaero-tube.

Fig. 2 is a plan View of a heated air dispersing motor and a base havingthe solenoid actuated aero-tube system suction device mounted thereon;

Fig. 3 is an enlarged sectional view of the diaphragm valve showing itsinterior construction and operation under suction;

Fig. 4 is an enlarged sectional View of the vent of the suction device;and

Fig. 5 is a fragmentary side View of the bracket connecting the solenoidplunger and the suction device.

The protective aero-tube I and the connected 35 conventional alarmmeans, generally denoted by A, is shown in Fig. l. The alarm means isconnected at a suitable point into the aero-tube and comprises a housingSil- 89, enclosing a flexible diaphragm which carries thereon a con- 40ductor contact button Sl. Beneath said button 9i is located anadjustable contact screw 92 which is threadedly mounted in an insulatorbushing 83, the latter being' suitably mounted in said housing 89. 45

The housing of the diaphragm and the contact screw92 are connected intoa normally open alarm circuit including a battery B and-an audible,electrically operated signal 94'. The upper chamber 96 of the housing isvented as at 95, so that the aero-tube system can breathe.

A sudden rise in air pressure in the aero-tube system causes thediaphragm 91!) to ilex downwardly, closing the alarm circuit and causingthe alarm to sound.

In Fig. 3 is shown a diaphragm actuated valve into the top of which, asat 2, is connected the open end of aero-tube I, the tube end beingtightly compressed, preferably, by a rubber packing 4, which is itselfcompressed by packing or compression nut 3 in the angled seat Ofthreaded end of upper extension 6. l

Extension 6 1-8 may be in a single piece as shown and it has: at itslower end a packing nut extension 8 which is threadedly engaged withthreaded nipple 9, said nipple and extension having associate angledpacking seats therein to compress a rubber packing I0, which in turnholds a replaceable tubular air restriotor II, the port of which may beof any desired diameter in accord with the desired volumetric air flowtherethrough, in point of time.

The nipple 9 has a lower ared wrench receiving portion I3 and isthreaded to receive therein the threaded end I3 of a tire valve-coreholding nipple 22, said core, generally denoted by a, being mountedtherein upside down, so as to pass? air from the upper diaphragm chamberb to the aero-tube I, but to seal itself against air passing downwardlyfrom said aero-tube I.

The upper end of the bore of nipple 22 may be made smaller as at I4, toform an annular ledge, against which the foot 25 of the core mayrestthereby to form an abutment for said foot under compressive actionof the valverspring 24 as it is compressed by the valve seat I5-I6 as itis screwed by its threaded outlet I1.

The lower end of nipple 22 is flanged as at I8 and by the lower threadedend is screwed firmly to the top face 21 of the diaphragm housing inthreaded bore 20. In this position the re- Y lief valve plunger 2i isheld in the upper chamber b of the diaphragm housing and adjacent theface of the diaphragm, generally denoted by 26, which is held clampedbetween the outer edges of the upper and lower housing sections 21 and29, respectively, by means of screws 30-30, Fig. 1. The central portionof the diaphragm is clamped by two opposing discs C d, xed together attheir centers with a fastening e.

The lower housing section 29 has an opening 28 permitting free movementof the diaphragm.

As shown in Figs. 1 and 3, especially the latter, the lower face ofhousing section 29 has mounted thereon a bracket f which slidablysupports therein a threaded bushing g, through a nonthreaded bore h andsaid threaded bushing is held in operative, adjustable relation in saidbracket by a pair of threaded nuts i and 7, the adjustment of whichmoves the bushing g up or down to increase or decrease the tension ofthe spring lc which is ailixed between the diaphragm fastening e and thethreaded end of bushing g, thus to bias the diaphragm to adjust it foraction under various tensions or pressures as' required.

It will be noted that a continuous air conducting passage is formed fromthe aero-tube system to the upper chamber b of the diaphragm housingwhich is controlled to be normally cut off by the valve I5 andvolumetric air ilow is constrained byV the restrictor II. Thus, normalchanges in the rate-of-rise pressure in the aerotube system do not getto the diaphragm.

The upper face of the top housing section 21 at one side, Fig. 3, isprovided with a threaded nipple 3| which coacts with a threadedcompressor nut 33 both the nipple and the nut having angled seats inwhich toreceive and compress a rubber packing 34 about the open end 35of a suction tube 36, to form a leak proof joint.

The tube 36, being broken for convenience, extends to the head 42 of theair extractor, generally denoted by 50, as shown in Figs. 1 and 2.

The connection of tube 36 to the extractor head 42 may be of anysuitable Ynature and must be air tight.

In Fig. l, the valved nippleY 22 oi Fig. 3 isl shown slightly reduced insize and the attached f tubing and upper portion of the nipple 22 isenclosed in a housing 38, which housing is shown in ltransverse sectionand which may be aiilXed to a support S in any suitable manner. Anyother mounting may be used.

The aero-tube I goes to the lprotected area from the open housing bossl39, the second or suction tube 36 being run in the direction of andcoupled to the head 42 by a tube connection 3l as shown in Figs. 1-2.

The suction device generally denoted by 50, Fig. 2, comprises the head42, which is xedly mounted to a base plate B, said head mounting acylindrical, tubular extension 48 in an airtight fit, the extension 48,in turn having its opposite open end 43 connected to the open end of ametallic Sylphon bellows 44, the opposite end of said bellows beingclosed by anV integral head 4I.

The head 4I mounts a piston or bellows: shaft 49 which extendsrearwardly through the open end 43 of bellows 44 and is connected to aU- shaped yoke 54 by having its reduced threaded end 52 passed throughunthreaded bore 55 in the closed end of said yoke. Two adjusting nuts56-51 spanning the closed end of the yoke are mounted upon said threadedend 52 and permit of adjustment between said rod 49, the yoke 54 and itsconnections, when setting up the apparatus. This adjustment may be alsoutilized to vary the maximum change in volumetric capacity of the airchamber 5I formed by bellows 44, when collapsed, and outer cylinder V48,by extending or contracting the bellows, thus varying, also, the strokeo, Fig. 2, of the solenoid plunger 6I.

The yoke 54, at its open end is connected to the stop head 58 ofsolenoid plunger 6I which is reciprocably mounted in the core. of amagnet M by a cross pin 59, Figs. 2 and 5. The stop head 58V has ears60--69 provided thereon to act as sto-p members and abut against theadjacent magnet face when the plunger is magnetically drawn backward inthe direction of the arrow T, Fig. 2. Y

The magnet is of known construction and comprises a solenoid 62 having acentral hollow core, and a magnet frame 63. The magnet is also Xed onbase plate B, with its plunger and core in substantial alinement withthe axis of rod 49.

The two terminals 64-65 of the magnet are connected into a circuit whichincludes a current source 18, connected to terminal 64 by wiring 66 anda normally open switch 69, the latter connecting one terminal of anelectric motor 'II by wire 68.

The other terminal of motor II is connected by wiring 61 to magnetterminal 65. The motor 1I mounts a fan 'I2 thereon, and when operating,the motor driven fan operates to propel heated air from an air heatingsource, not shown, into the protected room area.

The head 42, of the suction device, has provided thereon, in an airtight manner, a relief vent, which, as disclosed in Fig. 4, may be inthe form of a chambered nipple the threaded end 84 of which is screwedinto said head with its duct 8'! in Comunication with the air chamber 5Iof the suction device.

The interior of the nipple has mounted therein a porous leakage plug 86which is held in operative position by a threaded vent cap 83, the vent85, of which is openl to atmosphere. The plug 85 may be changed toincrease or decrease the air venting speed from chamber 5l.

The operation of the device is as follows:

The switch 69, Fig. 2, may be a thermostatic or a manual switch. Whenswitch t5 is` closed, the motor fan operates to drive heated air intothe protected area and simultaneously magnet M is operated to drawplunger El rearwardly in the direction of arrow T. This action contractsbellows i4 causing air to be sucked from the upper chamber b overdiaphragm 26 through tubing 35, 35 and 31 whereby the diaphragm 26 movesupwardly as shown dotted at D, Fig. 3, to contact with the end 2i oi theair valve and lift check valve I5 from its seat, whereupon the suctionaction of the bellows removes sumcient air from the protective aero-tubesystem to prevent it from sending an alarm.

Thus, it will be noted that the sudden rise of temperature caused by theoperation of the fan, which increases the air pressure in the aerotubesystem is negatived by the simultaneous withdrawal of air from theaero-tube system and after this is done the aero-tube system graduallyequalizes to the new temperature conditions through the breather vent 95in the detector alarm system A, the diaphragm 26 is restored to valveclosing position cutting off the aero-tube system from the diaphragm,and the aero-tube system is then in alarm sending condition under itsaltered temperature conditions.

It is understood that so long as the motor 1I operates to move heatedair into the protected area, the bellows is held contracted by themagnet M. As soon as the motor circuit is broken, the plunger 6l underrecovery action of the resilient bellows M- is restored to its initialoffset position, ready for a repetition of the cycle.

As the motor-magnet circuit is opened the plunger 6l and bellows Mi arerestored gradually to initial position by the gradual venting of air inbellows chamber 5l through the controlling porous restrictive vent 8S,the diaphragm 26 being lowered, and the valve l5 closed during thisrestoration.

The speed of restoration of the bellows dii and its connections SI-Sd-Llis controlled by the porous vent and this may be varied by replacementof the vent 36 with a porous vent member of greater or lesser ventingcapacity as circumstances require and indicate. This latter feature isof importance as the Vent 86 should not act too freely as it wouldprevent the instant action of the bellows on the air extraction line 36.

It will be noted that, due to the structure herein disclosed, that at notime is the aero-tube system I disabled against actuating the detectorsto send an alarm, because, at any degree of ternperature the xedrate-of-rise is set, and in any additional air adjustment in theaero-tube system by reason of a falling temperature or a greater thanthe set rate-of-rise increase in room temperature, the set rate-of-risein the aerotube system is constant. In the event that room temperaturehas reached the desired degree, and the blower heater is shutoff and theroom commences to cool on the aero-tube system adjusts itself, throughthe usual vent of the aero-tube system and the vent 85, to the changedtempera.- ture, but is ready at any temperature tobecome active. Thusthe present system maintains its set rate-of-rise during normal risingor falling temperature changes.

From the foregoing description of the valve, it will be noted that itacts as a check valve, to open or close communication between theaerotube system and the bellows actuating system, but it acts reverselyto the usual, known check valve structures, in that it closes when airpressures are created above the valve I5 in the aerotube system, whichmay be called the upstream or inlet side, and the valve I5 is opened bydownward suction created by the expanding suction action of the bellows44, upon what may be called the downstream or outlet side. In otherwords the upstream or inlet side of the structure is that portion of theducts or tubing above the valve and the downstream or outlet side of thestructure is that portion of the structure which is below the valve, asviewed in Figs. 1 and 3, where the complete valve is shown in normaloperative position. This valve can also be operated in the reverseposition to that shown in Figs. 1 and 3.

No claim is made herein to the broad concept of compensating means for afire detecting system arranged to prevent false alarms without renderingthe system inoperative, this sub-ject matter being claimed broadly inour copending application, Serial No. 164,286.

What we claim is:

1. The combination, with the aero tube of an aero alarm system adaptedto operate an alarm when the rate of pressure rise in the tube exceeds apredetermined rate, of a heater blower system adapted to cause in saidtube a rate of rise exceeding said predetermined rate; a. normallyclosed valve closing said tube; a diaphragm chamber having a wallcomposed of a flexible diaphragm means for opening said valve onmovement off the diaphragm when air pressure in the chamber is reduced;a suction device communicating with said housing; and electric circuitmeans having a circuit adapted to be closed for operating said heatersystem and including in said circuit an electro-magnetic operating meansfor operating the suction device for drawing air from the diaphragmhousing for opening said valve and then drawing air from the tube.

2. The combination, with the aero tube or an aero alarm system adaptedto operate an alarm when the rate of pressure-rise in the tube exceeds apredetermined rate, a heater blower system adapted to cause in said tubea rate of rise exceeding said predetermined rate and electric circuitmeans having a circuit adapted to be closed for operating said heatersystem, of a normally closed valve closing said tube and adapted to beopened to relieve pressure in the tube; a diaphragm chamber having awall composed of a iiexible diaphragm means for opening said valve onmovement of the diaphragm when air pressure in the chamber is reduced; asuction device communicating with said housing; an electro-magneticoperating means interposed in said circuit for ope-rating the suctiondevice when the circuit is closed for drawing air from the diaphragmhousing for opening said valve; said suction device having a slowventing device for equalizing exterior and interior pressures after apredetermined time to allow said valve to close.

3. A device for combination with the aero tube of an aero alarm systemadapted to operate an alarm when the Vrate of pressure-rise in the tubeexceeds a predetermined rate, a heater blower system adapted to cause insaid tube a rate of rise exceeding said predetermined rate; and electriccircuit means having a circuit adapted to be closed for operating saidheater system; said device comprising a normally closed valve adapted tobe connected for closing said tube and adapted to be opened to relievepressure in the tube; a diaphragm chamber having a wall composed of aiexible diaphragm means for opening said valve on movement of thediaphragm when air pressure in the chamber is reduced; a suction devicecommunicating with said housing; and an electro-magnetic operating meansadapted to be included in said circuit for operating the suction devicewhen the circuit is closed for drawing air from the diaphragm housingfor opening said valve; said suction device having a slow venting devicefor equalizing exterior and interior pressures after a predeterminedtime to allow said valve to close.

4. In combination, a pressure tube; a normally closed valve closing saidtube and adapted to be opened to relieve pressure in the tube; adiaphragm chamber having a wall composed of a exible diaphragm meansfor' opening said valve on movement of the diaphragm when air pressurein the chamber is reduced; a suction device communicating with saidIhousing; and an electric circuit means having a circuit adapted to beclosed and including in said circuit an electro-magnetic operating meansfor operating the suction device when the circuit is closed for drawingair from the diaphragm housing for opening said valve; said suctiondevice having a slow venting device for equalizing exterior and interiorpressures after a predetermined time to allow said valve to close.

5. 'I'he combination, with the aero-tube of an aero system adapted tooperate a' translating means when the rate of pressure-change in thetube exceeds a predetermined rate, of a temperature changing system;adapted to cause in said tube a rate of change exceeding saidpredetermined rate; a chamber communicating with the tube; a normallyclosed valve between said tube and chamber; a device communicating withsaid chamber for changing the pressure therein; means to open the valvewhen air-pressure in thechamber' is thus changed; and means foroperating said temperature change system including means for operatingsaid device.

6. In a combination as in claim 5, means to return the pressure in saidchamber to normal ber; means to open the valve when air is withdrawn;from the chamber; a suction device communicating with said chamber forwithdrawing air therefrom to open the valve and from the tube after thevalve is opened; means for operating said temperature change systemincluding means for operating said device.

9. In a combination as in claim 8, a slow venting device to allow air toreturn to said chamber to allow said valve to close.

10. The combination, with the aero-tube of an aero system adapted tooperate a translating means when the rate of pressure change in the tubeexceeds a predetermined rate, of a temperature changing system adaptedto cause in said tube a rate of change exceeding said predeterminedrate; a normally closed valve adapted when opened to allow the passagetherethrough of air from said tube; a chamber; means to open the valvewhen air in the chamber is changed; a pressure changing devicecommunicating with said chamber for changing pressure therein to openthe valve; and means for operating said temperature change systemincluding means for operating said device.

11. The combination, with an aero-tube fire alarm system, comprising anormally closed valve, an aero-tube, one end thereof being connected tosaid normally closed valve, al suction actuated diaphragm adjacent saidvalve and being normally unflexed, a heater blower system for causing arate of telnperature rise in said aero-tube nre alarm system at leastequal to the rate of rise necessary to operate the alarm, means operatedby the operation of the heater-blower to flex said diaphragm and opensaid valve to create a suction in said aero-tube, when the heaterbloweris in operation and means in connection with said diaphragm flexingmeans for operating to unex said diaphragm and to close said valve whenthe heater-blower ceases operating, and to restore normal conditions insaid aero-tube system.

12. The combination as set forth in claim 11,'

in which the normally closed valve comprises a chambered housingprovided with a ilexible diaphragm therein, one side of said diaphragmbeing open toatmosphere, the other side thereof being closed to theatmosphere, a tubular connection from said closed side of said diaphragmto a suction device, whereby suction flexes said diaphragm on saidclosed side away from said atmospheric side, said valve having an openduct connection into an aero-tube system on the closed side of saiddiaphragm, a valve seat between said open duct connection and theyclosed side of said diaphragm, a normally closed and' constrained valveon said seat, closing said closed side of said diaphragm from saidaero-duct connection, and

means connected to said valve and normally in.

operative contact with the closed side of said diaphragm, whereby whensuction is created on the closed side of said diaphragm the diaphragm isflexed out of normal to unseat said valve, thereby to extract air fromsaid aero-tube system and means connected to the atmospheric side ofsaid diaphragm for biasing the tension of lthe unflexed diaphragm toadjust the same to any desired degree of flexing displacement.

13. The combination, as set forth in claim 11, in which the valve is ofthe diaphragm operated type and includes a diaphragm, a normally closedvalve member ordinarily restrained upon its valve seat, meansoperatively connecting the valve member to the diaphragm whereby thediaphragm, when suction is applied thereto, opens said valve member fromits seat and means normally restraining said valve in its closedposition upon its seat, to resist application. of pressure upon saidvalve.

14. In a fire detecting system, an enclosure, an aero-tube arrangedtherein to supervise temperature changes and adapted to operate after apredetermined increase in pressure in said aerotube system, signal meanscontrolled by said aero-tube, a heat source adjacent said aero-tubesystem, an air extracting means connected to said aero-tube and meansfor simultaneously controlling said heat source and air extracting meanswhereby air will be extracted from said aerotube when said heat sourceis active to compensate the pressure changes and thereby prevent a falsealarm.

15. In a signalling system, an enclosure, an aero-tube system forsupervising changes in temperature in said enclosure, signal meanscontrolled by said aero-tube, a heat source adjacent said aero-tubesystem, an electrical circuit for controlling said heat source, abellows controlled by said electrical circuit and connected to saidaero-tube system for extracting air from said aero-tube when said heatsource is active to thereby prevent a false alarm.

16. In a signalling system, an enclosure, an aero-tube system forsupervising changes in temperature in said enclosure, signal meanscontrolled by said aero-tube, a heat source adjacent said aero-tube, anelectrical circuit for controlling said heat source, a bellows connectedto said aero-tube for extracting air therefrom, and a magnetic meanscontrolled by said electrical circuit for expanding said bellows wherebysaid bellows will extract air from said aero-tube system when saidelectrical circuit is closed.

FRANK M. COWAN. FRANCIS C. EVANS.

